A Question from a customer:
I have a 3dr telemetry kit that I was using with the APM board (bought something like a year ago), but the exit seems to be one pin short for the pixhawk board. What should I do?
They are using one of the older v1 3DR ratio telemetry modules which where designed for APM2.5, so they come with a 5pin connector, but the pixhawk board uses a 6pin connector. Below shows you some details as to how you can still use it.
You will need to modify a cable to connect it to the pixhawk as the older telemetry kits connect to APM 2.6 which has a 5pin telemtry port, but pixhawk uses a 6pin connector. My suggestion would be to buy this DF13 6pin cable and solder it to the cable that connects to the telemetry radio. The image below should help you wire it all togeher.